A conventional image-reading device has two separate reading units for reading each surface of an original sheet. When the conventional image-reading device described above reads an original sheet having an image formed on only one surface, there can be uncertainty as to which direction the surface containing an image is facing when the original sheet is conveyed along the original sheet-conveying path. In particular, if the image-reading device possesses a double-sided read function and this function is used frequently, the user may be uncertain as to which orientation to set an original sheet having an image on only one surface. The conventional image-reading device described above that possesses a double-sided read function is said to use this double-sided read function to read both surfaces of the original sheet, even when the original sheet has an image formed on only one surface. In this way, the image-reading device can read the surface of the original sheet on which an image is formed, regardless of the orientation of the original sheet when the original sheet is set in the image-reading device.